[名词解释] 胎盘嵌顿

脐带过短 脐带脱垂(prolapse of umbilical cord) 脐带帆状附着(cord velamentous insertion) 胎盘滞留 与食管癌关系密切的癌前病变的病理改变是() ["A．食管上皮增生","B．食管粘膜中性粒细胞浸润","C．食管粘膜淋巴细胞浸润","D．食管粘膜糜烂","E．食管粘膜充血水肿"] 胎盘嵌顿